I would assume so..
When did you last get a new phone or renew contract?
If it was a year then im pretty certain that you will be able to purchase an iPhone at the subsidized pricing.
If you can, check out wireless.att.com and check your upgrade eligibility. Right off the bat you will know. If eligible all set. Otherwise, find a friend with an old iPhone and activate your SIM chip in their phone and you will become eligible.